In this laboratory we have developed a family of polar, water- containing amino-plastic embedments for electron microscopy which permits the retention of lipids in sections, and which also maintains normal spatial relations dependent upon glycocalyx gels. Various staining procedures can be used to differentiate different layers associated with cytomembranes, secretory products and cytoplasmic inclusions. At the present time these techniques are being explored, particularly in relation to the formation and distribution of lung surfactant. It is intended in the future to apply these techniques in studying specific details associated with the kidney vascular system, particularly the fenestrated endothelium of the glomsruli, and the "slit- pores" associated with the glomerular podocytes to assess the distribution and role of surface coats found there. It is also intended that junctional complexes will be examined in kidney and intestinal epithelial cells to assess the role played by the glycocalyx, particularly in relation to "tight juncttons." It is intended also that the extracellular compartments created by the deep infoldings of the basal plasma membranes of tubular cells of the kidney will be studied with particular emphasis upon their dimensions.